Among thermoplastic resins, a polyester-series resin (such as a polybutylene terephthalate), a polyamide-series resin, or the like has excellent mechanical and electrical properties, weather resistance, water resistance, and resistance to chemicals and solvents. Therefore, the resin has been utilized for various purposes such as electric or electronic device parts, and automotive parts. While, these resins are required to have improved flame retardancy as the field of their uses expands.
Until now, there has been proposed a method for imparting flame retardancy to a thermoplastic resin by adding a flame retardant comprising a halogen-containing compound or an antimony-containing compound to the resin. For example, Japanese Patent Application Laid-Open No. 150349/1988 (JP-63-150349A) discloses a resin composition to which flame retardancy is imparted by blending a glass fiber, an organic halogen-containing flame retardant, antimony trioxide, and a hydroxide of an alkali metal or alkaline earth metal to a mixed resin comprising a polyamide resin and a nylon 66. However, the halogen-containing flame retardant is not preferable for environmental reasons because the flame retardant sometimes generates a dioxin-series compound on resolution caused by combustion. Therefore, there is proposed a method for rendering a resin flame-retardant by using a nitrogen-containing compound or a phosphorus-containing compound as a flame retardant having no halogen atom.
Japanese Patent Application Laid-Open No. 70671/1993 (JP-5-70671A) discloses a flame-retardant resin composition comprising (A) a polyalkylene terephthalate having an intrinsic viscosity of 0.3 to 1.5 dl/g, (B) a reinforcing filler, (C) an adduct of melamine and cyanuric acid, and (D) a resorcinol bisarylphosphate. Moreover, Japanese Patent Application Laid-Open No. 152402/1999 (JP-11-152402A) discloses a flame-retardant polyester composition comprising a reinforcing component and a polymer component, wherein the polymer component comprises a poly(butylene terephthalate), and a mixed flame retardant containing an aromatic phosphate oligomer, and a melamine pyrophosphate. Further, Japanese Patent Application Laid-Open No. 103973/2000 (JP-2000-103973A) discloses a flame-retardant resin composition comprising a thermoplastic resin, a phosphorus compound having a phosphonyl group (>P(═O)H), and a phenol resin.
The flame retardant having no halogen atom does not comprise harmful halogens, however, it is inferior to a halogen-containing flame retardant in flame retardancy, so that it is necessary to add a large amount of the flame retardant. The addition of a phosphate-series flame retardant or a phosphorus compound-series flame retardant having a phosphonyl group brings about bleeding out and deterioration in mechanical properties of a resin. Therefore, it is impossible to improve mechanical properties along with flame retardancy.
Thus, in conventional methods, it is difficult to render a resin high flame-retardant without deteriorating properties of the resin. Moreover, the above-mentioned flame retardant is capable of imparting flame-retardant to a specific resin, however, it is impossible to render a wide variety of thermoplastic resins flame-retardant.
It is therefore an object of the present invention to provide a flame-retardant resin composition having no halogen atom which is rendered flame-retardant to a satisfactory level with the use of a small amount of a flame retardant, and a process for producing the same.
It is another object of the present invention to provide a flame-retardant resin composition in which mold deposit and bleeding out (or blooming) of a flame retardant is effectively inhibited and to which high flame retardancy is imparted without deteriorating properties of the resin, and a process for producing the same.
It is still another object of the present invention to provide a shaped article having improved flame retardancy.